Updated 11:47 a.m. | In the aftermath of a meeting last month between Sen. Elizabeth Warren and Securities and Exchange Commission Chairwoman Mary Jo White, the Massachusetts Democrat is detailing her disappointment with the top securities regulator, including about campaign finance.

"I am disappointed by the significant gap between the promises you made during and shortly after your confirmation and your performance as SEC Chair. We have continued to talk, and you and I met personally on Wednesday, May 21, 2015, to discuss these issues," Warren wrote in a Tuesday missive to White. "At that meeting, however, you said little that indicated you would be changing your practices at the SEC."

White was quick to issue a statement refuting Warren.

"I am very proud of the agency’s achievements under my leadership, including our record year in enforcement and the Commission’s efforts in advancing more than 30 congressionally mandated rulemakings and other transformative policy initiatives to protect investors and strengthen our markets. Senator Warren's mischaracterization of my statements and the agency's accomplishments is unfortunate, but it will not detract from the work we have done, and will continue to do, on behalf of investors," White said.

Among Warren's criticisms of White was that the SEC has not moved forward with rules to require companies to promptly disclose political contributions.

"As you are well aware, there is overwhelming interest and demand in a corporate campaign spending disclosure rule: more than one million public comments in support of a 2011 petition to the SEC have called on the agency to set disclosure rules," Warren wrote.

Warren said the commission's response to a January 2014 letter from a group of senators led by Robert Menendez, D-N.J., as well as testimony to the House Financial Services Committee, demonstrated the SEC was not focused on the campaign finance disclosure question.

As part of a list of questions Warren wants answers to by the beginning of July, she wants White to outline why the campaign finance issue was taken off a list of possible regulations back in December 2013, as well has why the SEC has yet to respond to a relevant petition.

The complaints about inactivity on campaign finance disclosure is just one of many concerns that Warren's making public in her letter to White. The 13-page letter highlights that the SEC has not moved forward on a final rule on the disclosure of CEO pay that was a provision of the Dodd-Frank regulatory overhaul.

Warren wrote that an answer given by White about the timeline for finalizing that rule during the May 21 meeting with the senator appeared to conflict with the Office of Management and Budget's regulatory agenda publication that was released the same day. According to Warren's letter, White said the rule should be done by fall.

But Warren added in the letter, "newly published information from OMB indicates that the CEO pay rule is not expected to be finalized until April 2016, adding another six month delay compared to the previously posted OMB deadline."

And that apparent inconsistency particularly had the senator's attention.

"I cannot understand how and why this rule has been delayed for so long, and I am perplexed as to why you told me personally that the rule would be completed by the fall of 2015 when it appears that you were or should have been aware of additional delays," Warren wrote.

"I am disappointed that you have not been the strong leader that many hoped for — and that you promised to be," Warren said. "I hope that you will step up to the job that for which you have been confirmed, and that you will guide the SEC once again to meet its core mission of protecting investors and maintaining fair, orderly, and efficient markets."